This invention relates to a mine roof support system and more particularly to such a system which has elongated support members adapted to be moved into and out of abutting relation with a mine roof.
Heretofore in the art to which my invention relates, many systems have been proposed in the mining of coal and the like wherein temporary support means has been provided for the mine roof above a mining machine so that the roof is supported as the mining machine, such as a continuous miner, is operated between the mine face and the section of the mine roof supported by the usual roof bolts, timbers or the like. Such temporary means for supporting mine roofs must be operable to support the roof as the continuous mining machine advances into the mine face so as to prevent interruption of the mining operation, which would occur where it is necessary to disassemble and then reassemble the temporary roof supports each time the temporary roof support is advanced.
Conventional types of mine roof support systems are shown in U.S. Pat. No. 2,795,935, No. 2,795,936, No. 3,890,792, No. 3,534,560 and No. 4,143,991. The apparatus disclosed in the latter patent includes a plurality of truss members with each truss member being supported by a pair of prop members which are movable in a direction either toward or away from the mine face relative to the other pairs of prop members by telescoping devices that interconnect the prop members. Such apparatus is very difficult to stabilize and at the same time a considerable amount of time and effort is incurred in changing the relative positions of the individual pairs of prop members as each elongated roof engaging truss member is moved toward or away from the mine face.